This application proposes to develop a prototype software package for Intensity Modulated Radiation Treatment (IMRT) planning using the favorable characteristics of the Dynamically Penalized Likelihood (DPL) method of beam intensity optimization. Based on the premise that a Therapist wants to deliver a radiation dose to a treatment volume that is as high as possible, without regions of substantial over- or under- irradiation and as low a dose as possible to organs and tissues at risk, the DPL method constitutes a stable, controllable and fast method of calculation of optimum beam intensities fulfilling those requirements. After a successful proof-of-principle in a Phase I SBIR project, it is now proposed to carry out research to fully understand the relationship between algorithm parameters, doses prescribed to the different regions and medical end-points like Tumor Control Probabilities (TCP's) and Dose Volume Distributions (DVD's). It is further proposed to integrate the DPL algorithm into a commercial treatment planning system and to carry out comparative tests in the clinical environments of UCLA. The final goal is to generate an "optimization engine" that can be commercialized by incorporating it into the currently developing IMRT software packages of one or more radiation treatment equipment and software companies. PROPOSED COMMERCIAL APPLICATION: As a result of the work carried out in Phase I, there is already one commercial company interested in licensing the DPL algorithm, as is. The research to be carried out in Phase II is expected to demonstrate the excellent qualities of the DPL method for IMRT planning, which is now coming to the forefront as the correct way to treat patients with difficult tumors by radiation and for Radiosurgery. Further licensing of the method by other large commercial companies in the field is then expected.